ipn/ipnlocal: handle more edge cases in netmap expiry timer

We now handle the case where the NetworkMap.SelfNode has already expired and do not return an expiry time in the past (which causes an ~infinite loop of timers to fire). Additionally, we now add an explicit check to ensure that the next expiry time is never before the current local-to-the-system time, to ensure that we don't end up in a similar situation due to clock skew. Finally, we add more tests for this logic to ensure that we don't regress on these edge cases. Fixes #7193 Change-Id: Iaf8e3d83be1d133a7aab7f8d62939e508cc53f9c Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
2023-02-06 18:24:48 -05:00
parent 99b9d7a621
commit 6d84f3409b
3 changed files with 252 additions and 28 deletions
@@ -115,7 +115,7 @@ func TestFlagExpiredPeers(t *testing.T) {
 			if tt.controlTime != nil {
 				em.onControlTime(*tt.controlTime)
 			}
-			em.flagExpiredPeers(tt.netmap)
+			em.flagExpiredPeers(tt.netmap, now)
 			if !reflect.DeepEqual(tt.netmap.Peers, tt.want) {
 				t.Errorf("wrong results\n got: %s\nwant: %s", formatNodes(tt.netmap.Peers), formatNodes(tt.want))
 			}
@@ -123,6 +123,158 @@ func TestFlagExpiredPeers(t *testing.T) {
 	}
 }

+func TestNextPeerExpiry(t *testing.T) {
+	n := func(id tailcfg.NodeID, name string, expiry time.Time, mod ...func(*tailcfg.Node)) *tailcfg.Node {
+		n := &tailcfg.Node{ID: id, Name: name, KeyExpiry: expiry}
+		for _, f := range mod {
+			f(n)
+		}
+		return n
+	}
+
+	now := time.Unix(1675725516, 0)
+
+	noExpiry := time.Time{}
+	timeInPast := now.Add(-1 * time.Hour)
+	timeInFuture := now.Add(1 * time.Hour)
+	timeInMoreFuture := now.Add(2 * time.Hour)
+
+	tests := []struct {
+		name   string
+		netmap *netmap.NetworkMap
+		want   time.Time
+	}{
+		{
+			name: "no_expiry",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", noExpiry),
+					n(2, "bar", noExpiry),
+				},
+				SelfNode: n(3, "self", noExpiry),
+			},
+			want: noExpiry,
+		},
+		{
+			name: "future_expiry_from_peer",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", noExpiry),
+					n(2, "bar", timeInFuture),
+				},
+				SelfNode: n(3, "self", noExpiry),
+			},
+			want: timeInFuture,
+		},
+		{
+			name: "future_expiry_from_self",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", noExpiry),
+					n(2, "bar", noExpiry),
+				},
+				SelfNode: n(3, "self", timeInFuture),
+			},
+			want: timeInFuture,
+		},
+		{
+			name: "future_expiry_from_multiple_peers",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", timeInFuture),
+					n(2, "bar", timeInMoreFuture),
+				},
+				SelfNode: n(3, "self", noExpiry),
+			},
+			want: timeInFuture,
+		},
+		{
+			name: "future_expiry_from_peer_and_self",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", timeInMoreFuture),
+				},
+				SelfNode: n(2, "self", timeInFuture),
+			},
+			want: timeInFuture,
+		},
+		{
+			name: "only_self",
+			netmap: &netmap.NetworkMap{
+				Peers:    []*tailcfg.Node{},
+				SelfNode: n(1, "self", timeInFuture),
+			},
+			want: timeInFuture,
+		},
+		{
+			name: "peer_already_expired",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", timeInPast),
+				},
+				SelfNode: n(2, "self", timeInFuture),
+			},
+			want: timeInFuture,
+		},
+		{
+			name: "self_already_expired",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", timeInFuture),
+				},
+				SelfNode: n(2, "self", timeInPast),
+			},
+			want: timeInFuture,
+		},
+		{
+			name: "all_nodes_already_expired",
+			netmap: &netmap.NetworkMap{
+				Peers: []*tailcfg.Node{
+					n(1, "foo", timeInPast),
+				},
+				SelfNode: n(2, "self", timeInPast),
+			},
+			want: noExpiry,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			em := newExpiryManager(t.Logf)
+			em.timeNow = func() time.Time { return now }
+			got := em.nextPeerExpiry(tt.netmap, now)
+			if got != tt.want {
+				t.Errorf("got %q, want %q", got.Format(time.RFC3339), tt.want.Format(time.RFC3339))
+			} else if !got.IsZero() && got.Before(now) {
+				t.Errorf("unexpectedly got expiry %q before now %q", got.Format(time.RFC3339), now.Format(time.RFC3339))
+			}
+		})
+	}
+
+	t.Run("ClockSkew", func(t *testing.T) {
+		t.Logf("local time:  %q", now.Format(time.RFC3339))
+		em := newExpiryManager(t.Logf)
+		em.timeNow = func() time.Time { return now }
+
+		// The local clock is "running fast"; our clock skew is -2h
+		em.clockDelta.Store(-2 * time.Hour)
+		t.Logf("'real' time: %q", now.Add(-2*time.Hour).Format(time.RFC3339))
+
+		// If we don't adjust for the local time, this would return a
+		// time in the past.
+		nm := &netmap.NetworkMap{
+			Peers: []*tailcfg.Node{
+				n(1, "foo", timeInPast),
+			},
+		}
+		got := em.nextPeerExpiry(nm, now)
+		want := now.Add(30 * time.Second)
+		if got != want {
+			t.Errorf("got %q, want %q", got.Format(time.RFC3339), want.Format(time.RFC3339))
+		}
+	})
+}
+
 func formatNodes(nodes []*tailcfg.Node) string {
 	var sb strings.Builder
 	for i, n := range nodes {